UFO enthusiasts and true believers are celebrating the 66th anniversary of the Roswell Incident, the alleged crash of an extraterrestrial spacecraft outside the small town of Roswell, New Mexico in July 1947. The event marked the start of a wave of flying saucer sightings around the world. Inventors were quick to capitalize on the public’s mania for all things alien, filing numerous patent applications for everything from saucer-shaped salt and pepper shakers (USD161683) to advanced aircraft designs like the one above (US2718364). There’s even a CPC patent classification for flying saucers, B64C39/001. UFO hunters looking for evidence of alien technology in the patent record won’t find much. Aliens, it seems, prefer trade secrets.